Endoscopes are devices which allow visual examination inside a hollow cavity. In the field of medicine, the use of endoscopes permits inspection of organs for the purpose of diagnosis, viewing of a surgical site, sampling tissue, or facilitating the safe manipulation of other surgical instruments. Laparoscopes are used particularly for examining organs in the abdominal area. Laparoscopes typically include a light pipe for illuminating the region to be viewed, at least one lens assembly for focusing and relaying the image of the illuminated object, and a housing for the entire assembly which is structured to minimize tissue damage during the surgical procedure. The light pipe can include a fiber optic element for illuminating the site. The laparoscope housing includes a distal section that can be inserted within a body cavity and a proximal section which can include a handle that a user grips to position the distal end near the surgical site.
Existing laparoscopes can include an imaging device such as a charge coupled device (CCD). This solid state imaging system is used to capture an image of an object being viewed and convey it to a viewing device, such as monitor.
Currently, several problems exist with current laparoscope instruments. In laparoscope devices without a zoom system, in order for the viewer to obtain a closer view of an object, he has to adjust the position of the entire laparoscope manually. There is a risk of damaging or perforating soft tissues when the laparoscope is moved at a surgical site. Laparoscope devices containing zoom lenses also have drawbacks. After zooming on an object to be viewed, the user must focus the lenses on the object to obtain a viewable image. A continuing need exists, therefore, for improvements in endoscopic design to provide safer, more economical, and effective systems for examination of patients.
The invention relates to an endoscope device, and in a preferred embodiment, to a laparoscope having a tube with a proximal end and a distal end for insertion into body cavities or lumens for viewing of a site. The laparoscope can include, in a preferred embodiment, an illumination device, an imaging device, and a sheath having a lens system. The tube can comprise interlocking mechanisms to connect the sheath to the proximal and distal portions of the tube.
In a preferred embodiment, the illumination device is a fiber optic coupler and the imaging sensor can be a solid state imaging sensor, such as a charge coupled device or a two dimensional CMOS imaging device. The imaging device can be positioned at the distal end tube adjacent to the sheath lens systems.
The laparoscope can also include, in another embodiment, a sheath having a series of lenses that provides a zoom assembly. The laparoscope has a zoom control that actuates the zoom assembly. The zoom control can be mechanically operated, or in another embodiment, the zoom can be motorized. A finger operated switch on the handle can operate the motor or mechanically move the zoom assembly.
The front lens element on the sheath can be an objective lens which has a dual purpose. First, it is used to image the surgical area with the required resolution onto the solid state imaging sensor. Second, it provides a hermetic seal at the end of the sheath. The hermetic seal provides a sterile environment for the laparoscope. In one embodiment, the front lens element is a diffractive lens. Most optical systems of existing laparoscopes use four to six lenses to image the surgical area onto a camera. Each lens surface reflects as much as 4% of the incident light reaching the lens surface. Because these losses are cumulative, a six element objective lens can lose as much as 36% of the light from an image. A diffractive lens system can use only one lens and can have a loss of only about 8% of the light from an image.
The sheath with the zoom assembly can comprise a plastic having an index of refraction and an inner and outer layer of a lower index of refraction plastic. The sheath can also comprise a plurality of lenses as part of its zoom assembly. In a particular embodiment, there are four lenses in the optical system for the zoom assembly. In one aspect of this embodiment of the invention, the sheath includes a moveable inner sleeve and a stationary inner sleeve as part of its zoom assembly. The second and fourth lenses are mounted to the moveable sleeve and the first and third lenses are mounted to the stationary sleeve. During a zooming procedure, the second and fourth lenses translate linearly while the third lens element is caused to rotate within its housing by a cam mechanism. An advantage of this apparatus is that it is not necessary to focus the lenses following actuation of the zoom lens assembly to adjust the magnification. Thus the image of a particular region of interest can be magnified or demagnified to show a wider field of view without adjusting the focus of the optical system.
In a preferred embodiment, the lenses can comprise a molded plastic material. Existing laparoscopes incorporate expensive ground glass lenses in structures that are complicated and difficult to manufacture. Because of this, it has not been possible to manufacture laparoscopes or laparoscope components containing precision optics which are disposable and economically feasible for the user. Because the lenses of the present invention are plastic and relatively inexpensive, the sheaths having the zoom lens assembly are disposable after a single procedure and thereby reduce the sterilization needs for the system.
The invention can also include a sheath for changing the angle of view of an endoscope. The distal portion of the sheath can house the structure for changing the angle of view. In a preferred embodiment, this structure includes a prism. Viewing angles can be provided, preferably, between 30 and 45 degrees, however other angles an be used.
In a preferred embodiment, the laparoscope can include a handle at the proximal end of the system which the user can grasp and manipulate with one hand. The handle can comprise two portions attached by a connector which hermetically seal the proximal end. The handle surface can also comprise a plurality of surface ridges and depressions. The handle allows the proximal end of a laparoscope to remain sterile during a surgical procedure. The handle can be made from plastic, allowing for economic disposal after the laparoscopic procedure is completed. The connector can be disengaged using a push button manual release. The handle permits one-handed use of the laparoscope, allowing the user a free hand to perform other tasks.
The invention further relates to a method of using a laparoscope and sheath assembly. The method involves placing a sheath on a laparoscope, placing the laparoscope within a surgical area, adjusting a zoom control to view an object and removing the laparoscope from the surgical area. The sheath can then be removed from the laparoscope and replaced with a sterile sheath. The method can then be repeated for a different patient while maintaining the sterility of the instrument.
In another preferred embodiment of the invention the laparoscope tube and the sheath can be flexible so that the user can orient the tube in a curved shape to afford viewing at a different angle. This embodiment can employ a distally mounted zoom assembly optically coupled to an imaging sensor as described previously herein. The sheath and inner tube of the assembly are made with a flexible hermetically sealed tubes having a shape memory so that the user can manually manipulate the flexible section into the desired shape and insert the distal end into a bodily cavity without losing the shape. The system can also incorporate cable or other mechanical or motorized elements so that the user can reposition the distal flexible section while still within a cavity during a procedure.